Studies on The Mitotic Chromosomes and Meiotic Synaptonemal Complexes (SC) of Chinese Pangolin (Manis pentadactyla)

A new karyotype of Chinese pangolin (Manis pentadactyla) was studied by C-banding,silver staining and analysis of synaptonemal complexes of spermatocytes.The karyotype reported in this paper is characterized by a diploid chromosome number of 40,with constitutive heterochromatin on centrimeric,distal and interstitial regions of chromosomes.Ag-NORs,with different activities in cells,were found to be located on chromosomes 18 and 19 respectively.Observations on synaptonemal complex show that the pairing between some areas on X chromosome and Y chromosome,forming loops along the X.Y axes,is later than others,which may imply the existence of nonhomologous pairing and synaptic adjustment in the pairing of sex chromosome of Chinese pangolin.Based on the comparative studies of on karyotype of the same species in literature and our observations on chromosomes of Chinese pagolin (M.pentadactyla),the chromosome polymorphism and possibile mechanism of the karyotypic evolution of M.pentadactyla are also discussed.